On Feb 28, 2011, at 11:59 AM, Tom Lane wrote: > Robert Haas <robertmh...@gmail.com> writes: >> On Sun, Feb 27, 2011 at 8:33 PM, Joachim Wieland <j...@mcknight.de> wrote: >>> Remember that it's not only about saving shared memory, it's also >>> about making sure that the snapshot reflects a state of the database >>> that has actually existed at some point in the past. > >> But you can do all of this with files too, can't you? Just remove or >> truncate the file when the snapshot is no longer valid. > > Yeah. I think adopting a solution similar to 2PC state files is a very > reasonable way to go here. This isn't likely to be a high-usage or > performance-critical feature, so it's not essential to keep the > information in shared memory for performance reasons.
Dumb question: Is this something that could be solved by having the postmaster track this information in it's local memory and make it available via a variable-sized IPC mechanism, such as a port or socket? That would eliminate the need to clean things up after a crash; I'm not sure if there would be other benefits. -- Jim C. Nasby, Database Architect j...@nasby.net 512.569.9461 (cell) http://jim.nasby.net -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers